For example, as disclosed in Japanese Patent Application Kokai Publication No. 2001-036315, a conventional vehicle roof-mount antenna is fixed to a vehicle roof in such a way that a screw boss protruding from an antenna base is inserted into a mounting hole formed through the vehicle roof, and a nut is fastened to the screw boss from a vehicle interior side. In such a configuration, a worker may be in danger of dropping the nut during mounting work, or workability may be deteriorated since the worker makes the fastening from the vehicle interior side through the vehicle roof.
To solve such deterioration of workability, Japanese Patent Application Kokai Publication No. 2006-248486 filed by the same applicant as the present application discloses a roof-mount antenna mounting structure capable of facilitating the mounting of the antenna to the vehicle and thus reducing a burden on a worker. The mounting structure uses a leg washer and is inserted into a mounting hole formed through a vehicle roof from outside a vehicle interior. Then, in association with the fastening of bolt and the like, leg portions of the leg washer abut against an abutment portion formed in a screw boss to be spread, with the result that claws of the respective leg portions bite into a vehicle interior side of the vehicle roof, whereby fixing to the vehicle roof and electrical connection to (grounded to) the vehicle roof can be achieved.
Further, as a structure for preventing deformation of the washer portion of Japanese Patent Application Kokai Publication No. 2006-248486, a roof-mount antenna mounting structure using a reinforcing plate disposed so as to overlap the washer portion is disclosed in Japanese Patent Application Kokai Publication No. 2011-194949 filed by the same applicant as the present application.